Dynamic behaviour of materials

The RV division is developing advanced dynamic testing methods based on high-speed hydraulic jack (6 m/s, 300 kN), Hopkinson bars and plate impact gas launcher (D80-120 mm, 1000 m/s; Brittle’s CODEX chair) to characterize the behaviour of materials over a wide range of strain rates (1 s-1 - 1E5 s-1). The instrumentation used consists in laser interferometers and ultra-high speed cameras for performing full-field measurements (DIC or grid method) or direct visualization. These experimental data feed the constitutive models used in numerical codes. On a numerical point of
view, RV is developing two approaches in parallel:

• The discrete-element method (DEM), which offers obvious advantages in terms of representation of discontinuities (cracking, fragmentation)
• The finite-element method (FEM) integrating nonlinear phenomena associated with damage processes in brittle materials

These activities are carried out by implementing innovative methods and tools:

• in experimentation: mechanical characterization tests on a wide range of loading speeds coupled with ultra-high speed imaging instruments and kinematic field measurements (DIC, grid, interferometry) (ExperDYN platform), mechanical tests on structures (DESSIS test platform), mechanical tests under deviatoric stresses (GIGA / BCR3D) and high temperature tests.
• in numerical modeling: multi-physical approaches, discrete (DEM ) and continuous (FEM) approaches at mesoscopic and structure scales, propagation of uncertainties at different scales.